• Korean Journal of Applied Biomechanics
• /
• v.33 no.1
• /
• pp.17-24
• /
• 2023

Objective: The purpose of this study was to investigate the effects of different frequency on of knee extensors muscle function during electrical muscle stimulation (EMS). Method: In this research, 40 subjects who have no musculoskeletal disorder, and less than a year workout experience were recruited in order to analyze effects of EMS with different stimulus frequency. Forty subjects were randomly divided into four groups of ten subjects in each group. A EMS training program with different frequencies (without EMS [WE], EMS with frequency 30 Hz [E30], EMS with frequency 60 Hz [E60], EMS with frequency 90 Hz [E90]) was assigned to each group. Throughout eight weeks of training, test subjects were simultaneously carried out knee extension exercises such as squat, leg extension, and leg-press while using EMS with different frequency (20 min, pulse width 250 ㎲, on-off ratio 1:1). Isokinetic knee extension strength, muscle activity of the rectus femoris (RF), the vastus medialis (VM), and the vastus lateralis (VL), and the median frequency of the RF, the VM, and the VL were collected and compared between pre and post training in order to find effects of applying EMS with different frequencies. For each dependent variable, a one-way ANOVA was to determine whether there were significant differences among four different conditions (p<.05). When a significant difference was found, post hoc analyses were performed using the contrast procedure. Results: When compared to WE and E90, E30 causes significant increase in isokinetic knee extension strength. No significant differences were found in EMG values across different EMS conditions. However, the median frequency of the VM in E30 was significantly increased than the corresponding value for WE. Conclusion: The results of this study showed that EMS training with 30 Hz frequency had positive effect on knee extensor. Based of the findings of the present study, EMS training with lower frequency may help the performer to focus on developing strength in knee extensor muscles.

• Korean Journal of Applied Biomechanics
• /
• v.16 no.4
• /
• pp.73-81
• /
• 2006

The purpose of this study was to investigate the effects of strength training on knee joint torque during walking in an adolescent with trisomy-21 Down syndrome. One adolescent with Down syndrome and one normal child participated in this study. Strength training consisted of eight exercises: squat, hamstring curl, hip adduction, hip abduction, knee extension, toe raise, sit-ups, and hyperextension of the waist. The participant with Down syndrome was participated in strength training for 12 weeks, three times a week, three sets, 10-15 RM; resistance was adjusted according to the principle of progressive overload. To measure the effect of strength training, isokinetic strength variables and knee joint torques were measured before training and after 12 weeks of training. The participant with Down syndrome had some abnormalities in controlling knee motion during walking due to muscle hypotonia, ligament laxity, and weakness of muscles. Post-training isokinetic strength increased compared to pre-training measurements. Knee range of motion were increased after strength training. Strength training did not affect ad/adduction and in/exteranl moments but did have an effect on flexor/extensor moment and timing.

• Journal of Advanced Technology Convergence
• /
• v.1 no.1
• /
• pp.33-42
• /
• 2022

The flexors and extensors of the knee joint are essential for maintaining body stability. The purpose of this study was to investigate the correlation between the isokinetic parameters of the knee flexor and extensor muscles and the function of the lower extremity muscles. Twenty-two healthy adults participated in this study. The time to peak torque (TTP), acceleration time (AT), and peak torque (PT) of the knee flexor and extensor muscles were measured. A 20m sprint, Sargent jump, one leg hop test, and side shuffle were measured to evaluate lower extremity function. The correlation between each variable was analyzed using Pearson correlation coefficient. PT of the knee flexor showed a significant correlation with single leg hops and 6M hops in a single leg. PT of knee extensors was found to be significantly correlated with Sargent jumps and triple hops. Based on the results of this study, we suggest that the strength of the knee flexor and extensor muscles has the potential to be used to predict lower extremity function.

• Journal of the Korean Society of Physical Medicine
• /
• v.6 no.3
• /
• pp.267-275
• /
• 2011

Objective : This study aims to examine how lumbar stabilization exercise and resistive exercise affect lumbar and lower extremity muscular strength of the aged. Method : Randomly selected 15 female senior citizens aged 65 or older at S, Y, and J senior citizens' center located in D city who meet the requirements for the study were divided into a resistive exercise group of 7 and a stabilization exercise group of 8 for which 60-minute-exercise sessions were administered three times a week for 12 weeks. Measuring lumbar and lower extremity muscular strength was measured six weeks and 12 weeks after exercise, respectively. Results : First, both resistive exercises and stabilization exercises are effective to improve lumbar muscular strength. Second, resistive exercise is effective to improve flexural muscle strength as well as lower extremity muscular strength, and stabilization exercise is effective for both flexion and extensor muscle strength. Conclusion : The 12 week lumbar stabilization exercise program appeared to be effective to improve lumbar and lower extremity muscular strength of the aged. This indicates that applying this program to identify and prevent frequent risk factors of falling can lead to the prevention of secondary problem factors of falling accidents.

• Journal of the Korean Society of Physical Medicine
• /
• v.14 no.4
• /
• pp.1-8
• /
• 2019

PURPOSE: The purpose of this study was to compare the maximum knee strength and endurance of elderly Korean women with Kellgren-Lawrence grade (K-L II) by age. METHODS: In this study, the total number of participants was 50, divided into five groups of 10 by age. Maximum knee muscle strength was measured at a low speed of 60°/sec using Biodex, an isokinetic device for comparison of maximum knee muscle strength, whereas muscle endurance was measured by muscle contraction at a high speed of 180°/sec. The peak torque values of the extensor and flexor muscles in the muscle strength and muscle endurance tests were collected according to each classification. RESULTS: The results of the experiment show that maximum muscle strength and muscle endurance decreased significantly at 60°/sec and 180°/sec during flexion and extension according to age (p<.05). In particular, the age group of 71 to 75 years showed the most significant correlation with other age groups (p<.05). CONCLUSION: The results of this study can be used as basic data for increasing physical activity and muscle strength in women with knee osteoarthritis.

• PNF and Movement
• /
• v.18 no.1
• /
• pp.55-64
• /
• 2020

Purpose: The purpose of this study was to compare the strength and walking ability of chronic stroke patients following either proprioceptive neuromuscular facilitation (PNF) pattern training with pressure biofeedback units (feedback group) or PNF pattern training without pressure biofeedback units (control group). Methods: Eighteen participants with chronic stroke were recruited from a rehabilitation hospital. They were divided into two groups: a feedback group (n = 8) and a control group (n = 10). They all received 30 minutes of neurodevelopmental therapy and PNF training for 15 minutes five times a week for three weeks. Muscle strength and spatiotemporal gait parameters were measured. Muscle strength was measured by hand-held dynamometer; gait parameters were measured by the Biodex Gait trainer treadmill system. Results: After the training periods, the feedback group showed a significant improvement in hip abductor muscle strength, hip extensor muscle strength, step length of the unaffected limb, and step time of the affected limb (p<0.05). Conclusion: The results of this study showed that proprioceptive neuromuscular facilitation pattern training with pressure biofeedback units was more effective in improving hip muscle strength and walking ability than the proprioceptive neuromuscular facilitation pattern training without pressure biofeedback units. Therefore, to strengthen hip muscles and improve the walking ability of stroke patients, using pressure biofeedback units to improve trunk stability should be considered.

• The Journal of Korean Physical Therapy
• /
• v.10 no.2
• /
• pp.33-40
• /
• 1998

This study was carried out to investigate the muscle strength of quadriceps muscles by means of isokinetic test. The experimental objects were devided into electrically stimulated, isotonic and isometric groups and trained for 4weeks. The results were as follows : 1. the values of total work, peak torque, average power and the ratio of peak torque between flexors and extensors revealed singnificant statistically in three experimental groups(p<0.05). 2. The endurance was increased slightly in electrically stimulated group, but decreased in isotonic and isometric group, 3. The value of post training on all items did not reveal significant statistically in three experimental groups(P>0.05). 4. The electrically stimulated groups effected on increasing of muscle strength as isotonic and isometric exercises.

• Journal of Korean Physical Therapy Science
• /
• v.14 no.1_4
• /
• pp.1-10
• /
• 2007

The purpose of this study was to find the effects of the lumbar stabilizing exercise on the isometric lumbar extension strength and the range of motion of lumbar extension. 16 healthy subjects were recruited (9 males, 7 females, mean age 25${\pm}$3.2). They performed 5 types of exercises 5 times per week for 4 weeks. We evaluated isometric trunk extension strength (0, 12, 24, 36, 48, 60, $72^{\circ}$) by MedX(Ocala, FL) and measured range of motion of lumbar extension. All measurements were measured at pre-exercise and 4 weeks post-exercise. The results of this study were summarized as follows; After 4 weeks of exercise, isometric lumbar extension strength was generally increased but there were only significant differences at $12^{\circ},\;24^{\circ},\;48^{\circ}$. The range of motion of lumbar extension was increased (p<.05). The isometric lumbar extension strength correlated with the range of motion of lumbar extension. In conclusion, our results have shown that lumbar stabilizing exercise influenced both lumbar extension strength and range of motion of lumbar extension.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.17 no.10
• /
• pp.628-634
• /
• 2016

Many pitchers suffer from various types of injury (distortion, sprain and so on). The rate of injury is increased if there are differences in strength between the extensor and flexor muscles when a joint movement is performed with maximum speed. However, there has been insufficient research into the injury caused by strength differences between the extensor and flexor muscles. Thus, the purpose of the study was to examine the effects of elbow ulnar collateral ligament injury on the maximal isometric strength in young baseball pitchers. The data collection was conducted for 2 weeks. The subjects (n=36) who participated in this study were placed into either the injury group (n = 18, IG) or normal group (n = 18, NG). The maximal isometric strength for the pectoralis major (PM), infraspintus (I), biceps brachii (BB), triceps brachii (TB), flexor carpi radialis (ECR) and extensor carpi radialis (FCR) muscles were determined by an isometric strength machine (K-DFX) and then the differences in strength were calculated by muscle group. All of the data were analyzed by SPSS 18.0 with the independent t-test. In the results, the maximal isometric strengths in the IG for the I (p=0.035), BB (p=0.031) and TB (p=0.041) were significantly lower than those in the NG, while that for the ECR (p=0.047) was significantly greater. In addition, the differences of the maximal isometric strength between the PM and I (p = 0.008), BB and TB (p = 0.002), and FCR and ECR (p = 0.032) in the IG were significantly greater than those in the NG. In conclusion, the differences in muscle strengths of the subjects in the IG were greater than those in the NG, which suggests that they might have a higher injury rate in the future. However, they might be able to recover from their injury and achieve better performance if the differences in strength were reduced by training.

• The Journal of Korean Physical Therapy
• /
• v.19 no.6
• /
• pp.23-30
• /
• 2007

Purpose: This study examined the correlation between the maximum voluntary isometric contraction (MVIC) and the muscle architecture in the extensor carpi radialis longus muscle during MVIC. Methods: The muscle area, volume were measured using a ultrasound imaging system to obtain the muscle architecture during the MVIC. For the mechanical muscle strength measurements, the MVIC was obtained using a dynamometer. Results: There was a significant correlation between the MVIC and the muscle area (r=0.498, p<0.01) and muscle volume (r=0.602, p<0.001). There was a significant correlation between the MVIC and density (r=-0.429, p<0.05). The area showed significant correlations with the muscle volume (r=0.699, p<0.001) and density (r=-0.429, p<0.05). In addition, there was a correlation between the volume and muscle density (r=0.555, p<0.01). Conclusion: There is close relationship between the MVIC and the muscle architecture in the extensor carpi radialis longus muscle during the MVIC.